Removing oxidation from 18KY

[fbroz]

Hello

I have been asked to clean up a beautiful pendant and earring set
from Gumps. It is 18KY and set with pink coral and diamonds. Other
than tarnish- darker coloration in recessed areas it appears almost
new. Any suggestions on how to safely clean would be most welcome.

Regards
Franz

[Judy_in_Kansas]

Hello Franz,

The coral is the sensitive part. I use an ionic cleaner to remove
tarnish on pieces with pearls. No damage to the pearls, so coral
should not be harmed.

Now why did 18KY tarnish? That is a worthwhile question - did the
owner expose the pieces to some sort of chemicale Is the dark
coloration intentional? Just wonderin’.

Judy in Kansas, where rain has been falling heavily for a couple
hours. Nowthat the wheat is close to harvest, the rain presents a
problem!

[Elliot_Nesterman]

I have been asked to clean up a beautiful pendant and earring set
from Gumps. It is 18KY and set with pink coral and diamonds. Other
than tarnish- darker coloration in recessed areas it appears
almost new. Any suggestions on how to safely clean would be most
welcome. 

As 18K doesn’t tarnish, most likely you are looking at a patina
applied for contrast. I’d just use a very soft brush and warm water
with a bit of soapy ammonia to remove any dirt that may have
collected, but don’t try to remove the patina; it’s part of the
design.

Elliot Nesterman

[rebecca_rourke1]

I’m a bit curious as to who told you it’s 18 Kt gold? Did you see a
standards mark? It shouldn’t have tarnish on it at all- the SOLDER
however may be what you are seeing! if it was a bad solder job and
was sweated on it sounds like it leaked under some mystery metal. I
would have the client sign a waiver before you agree to work on it
(if you are truly concerned and are inexperienced.) to the effect of
you will perform a scratch test and based on the indication you will
clean the metal appropriately however you are not responsible should
it be marked 18 Kt Y and it is, in fact, not that alloy or have the
piece brought to you for a preliminary inspection and to give a
reasonable estimate. At that time explain the potential problems- if
the person wants to hear it- Some clients just want it done and
would rather sign a paper than understand the process PROTECT
YOURSELF if you feel you are qualified to take it on, which involves
admitting the job is beyond your current skill set! - Though you may
know how to deal with different alloys you don’t know what the stuff
is if it’s tarnished! As for the coral- distilled water in an
ultrasonic very briefly- if at all- you can clean that by hand with
cotton swabs, remember no acids on it whatsoever! best of luck, rer

[fbroz]

Thanks for all your replies and suggestions.

These pieces belong to a 90+ year old woman who has better eyes than
this 60 year old jeweler.

I ended up cleaning in very mild dish washing soap in warm water in
ultrasonic. Tried not to let coral get exposed and brushed lightly.
Then water rinse. This did clean pieces but had no effect on orange
tinge. See pics below.

Regards
Franz

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[jhaemer52]

Elliot- Please no ammonia on coral. It will ruin the finish.

Mild soap and warm water only. Fabulustre, tin oxide, Twinkle brand
silver polish, or crystal polish for polishing. I’d use a Q-Tip or a
very soft small bristle brush with one of the above.

Any polishing compounds with color such as red, blue, or green
rouge. are likely to stain the lighter coral as well.

Jo Haemer
timohtywgreen.com

[Elliot_Nesterman]

Thanks, Jo. I haven’t worked with coral for years.

Elliot Nesterman

[Elliot_Nesterman]

This piece may have originally been plated with a rose gold alloy.
Note how pink the metal is around the diamonds.

Rose gold was very popular in the 40s and 50s. It looks as though it
was rose-gold plated and the plating has been polished away by
someone overzealous.

[jbin]

I'm a bit curious as to who told you it's 18 Kt gold? Did you see
a standards mark? It shouldn't have tarnish on it at all- the
SOLDER however may be what you are seeing! 

Sorry but 18k and even 22k will tarnish in the right circumstances.
Read this piece from Dr Christopher Corti of the World Gold Council

Gold Jewellery Tarnishing - Ganoksin Jewelry Making Community

James Binnion

[fbroz]

Sorry but 18k and even 22k will tarnish in the right
circumstances. Read this piece from Dr Christopher Corti of the
World Gold Council
http://www.ganoksin.com/borisat/nenam/wgc-gold-karat-tarnish.htm 

Thank you James.

Regards
Franz

PS I consult your Jewelry Metals book regularly. It it very well
done.

[jhaemer52]

Thanks Jame Binnion.

I remember that a lot of the gold jewelry that came out of Thailand
and Hong Kong in the 60s and 70s, the Viet Nam War era, tarnished
much like the coral earrings.

We use to joke in the trade that the gold was alloyed with old Jeep
parts.

Have fun and make lots of jewelry.

Jo Haemer
timothywgreen.com

[fbroz]

Update.
I had another trade customer who had 2-18K rings that had tarnished. Said her customer had not worn and stored in jewelery box. They were set with tourmaline and diamonds, not coral.So after polishing I was going to 18KY gold plate to remove tarnished area in bright cuts and recessed areas. To my surprize after electro clean all tarnish was gone and no need to plate.

Thought I would pass this along.
Regards
Franz

[aloped]

Hello Franz,

I never heard of 18KY gold tarnishing in time.
I just thinking loud, is it realy 18K?
The lowest karat gold which will tarnish in time is 9 up to 10KY depending
on how the alloy is made.

Gold plating over tarnisch is not a proper way to remove tarnish.
First step in goldplating is cleaning your jewelry in order to have a good
clean surface for the plating solution.
Tarnish is removed by polishing, electro cleaning.or chemical way, never by
plating.

[scavengerqr]

Might be 18kge. Gold electroplate. Or 1/20 gold filled. Gold shouldn’t
tarnish. Buffing should take off surface blemishes. If it’s gold no need
to plate

[jhaemer52]

I have seen 18 KT and 14 KT tarnish. See my post on the this from a while back. Also electro cleaner is mostly cyanide. It’s just a basic cyanide bath. I heat it a bit and just immerse what I want to remove tarnish from. No electricity needed. Do not do this on pieces that have porous stones like malachite, lapis, turquoise, pearls or coral.
Have fun and make lots of jewelry.
Jo Haemer
www.timothywgreen.com

[tomt]

I think you mis-spoke here. Electro cleaner is not mostly cyanide, More likely it’s TSP based (Tri-Sodium_Phosphate).
However, Electro Stripping solutions are Cyanide based and will do as you mentioned in your post. One caveat though, If you have stripped a large amount of jewelry with the solution, the solution will actually back plate silver if no current is used. Scary at first but easily rectified with a bit of current as if you intended to strip all along. I wouldn’t do this with a polished piece of jewelry. I use Blitz cleaners in my Ultrasonic and this actually does a fair job by itself. Your stone warnings apply here also. A straight cyanide solution will also work very well. It works almost instantly when warmed but not for prolonged soaking. It will etch the metal.

[tomt]

As far as 18k tarnishing, it depends on where and how it was stored. Some chemicals in dyes and glues and even wood itself in jewelry boxes will cause tarnish. Also two dissimilar metals touching will cause what is caused a galvanic reaction over time causing tarnish. I’ve seen several cases of this in my career. For those not familiar with the West coast, Gumps is a prestiege brand located in the San Francisco area. So not likely to be something plated.

[jhaemer52]

Tom you are so right! I just jumped up and looked in my chem cabinet. Yup.
Electro striping. And yes I do prefer straight cyanide but it is so hard to
get these days I’m just using up my old electro striping salts.
I humbly bow to your superior knowledge.
Have fun and make lots of jewelry.
-Jo Haemer
www.timothywgreen.com
PS: When we lived in the bay area we used to luuuuv going to Gumps and the
De Young Museum

[fbroz]

Thanks Jo and Tom.

To be clear I used electroking electrocleaning solution mixed @ 1/4 lb to gal of distilled water. it was heated to 120 F and gave 2 minutes with rectifier @ 6volts as per spec. I think tanish was gone in seconds.

Have used plating in the past to hide discolorations. Sometimes doing copper, silver, gold or palladium before final plating. I use to do electro striping and still have almost a full qt but just have not done in 20 years.

A word of warning to any who plan to plate, you must have a well evacuated hood and use protective gear.

Regards
Franz
PS I was raised In SF bay area and never went to Gumps but of course to the DeYoung. My wife had her ears pierced @ Samuels jewelers by old man Samuels. After moving to the monterey peninsula I was asked by a gumps contractor to make his steel rings. He is long gone and his work seems to be worth plenty. Glad i made the right choice…